According to the findings of a new study, stress actually alters your brain on the most fundamental level. So, lay off, mum.

The oft-repeated goal of many is avoiding toxic people in the new year. Of course, we come to this conclusion not on the basis that we believe they’re actually harmful to our health, we just assume that whatever they’re doing is not beneficial, so off to the social glue factory they must trot. What we lack is evidence.

However, it seems that those who bring the most superfluous stress to your life are actually doing you harm, as one University of Calgary study believes that exposure to stress literally changes your mind, altering it on the most physical of levels.

Jaideep Bains, PhD at the brilliantly named Cumming School of Medicine’s Hotchkiss Brain Institute, believes “brain changes associated with stress underpin many mental illnesses including PTSD, anxiety disorders and depression…recent studies indicate that stress and emotions can be ‘contagious’. Whether this has lasting consequences for the brain is not known.”

To test their hypothesis, the team studied the effects of stress in pairs of male or female mice. They removed one mouse from each pair and exposed it to a mild stress before returning it to its partner.

They then examined the responses of a specific population of cells which control the brain’s response to stress in each mouse, which revealed that networks in the brains of both the stressed mouse and naïve partner were altered in the same way.

“What was remarkable,” according to Toni-Lee Sterley, a postdoctoral associate in Bains’ lab and author of the study, “was that CRH neurons from the partners, who were not themselves exposed to an actual stress, showed changes that were identical to those we measured in the stressed mice.”

The team discovered that the activation of these neurons cause the release of a chemical signal, an “alarm pheromone”, from the mouse that alerts the partner. The partner who detects the signal can in turn alert additional members of the group. Cue waves of stress, and surf is definitely up.

According to Bains, the findings are easily transferable to people. “We readily communicate our stress to others, sometimes without even knowing it. There is even evidence that some symptoms of stress can persist in family and loved ones of individuals who suffer from PTSD.”